Data from: Assessing specialized metabolite diversity in the cosmopolitan plant genus Euphorbia L.

Coevolutionary theory suggests that an arms race between plants and
herbivores yields increased plant specialized metabolite diversity and the
geographic mosaic theory of coevolution predicts that coevolutionary
interactions vary across geographic scales. Consequently, plant
specialized metabolite diversity is expected to be highest in
coevolutionary hotspots, geographic regions, which exhibit strong
reciprocal selection on the interacting species. Despite being well
established theoretical frameworks, technical limitations have precluded
rigorous hypothesis testing. Here we aim at understanding how geographic
separation over evolutionary time may have impacted chemical
differentiation in the cosmopolitan plant genus Euphorbia. We use a
combination of state-of-the-art computational mass spectral metabolomics
tools together with cell-based high-throughput immunomodulatory testing.
Our results show significant differences in specialized metabolite
diversity across geographically separated phylogenetic clades. Chemical
structural diversity of the highly toxic Euphorbia diterpenoids is
significantly reduced in species native to the Americas, compared to
Afro-Eurasia. The localization of these compounds to young stems and
roots, suggest a possible ecological relevance in herbivory defense. This
is further supported by reduced immunomodulatory activity in the American
subclade as well as herbivore distribution patterns. We conclude that
computational mass spectrometric metabolomics coupled with relevant
ecological data provide a strong tool for exploring plant specialized
metabolite diversity in a chemo-evolutionary framework.